We’re learning that comets are ever more badass and more bizarre, thanks to to the European Space Agency’s Rosetta orbiter. The little bugger has been circling around comet 67P/Churyumov–Gerasimenko since last August, gathering data on its quirks. The latest discovery: sinkholes on the rock’s surface.

In a study published in Nature today, an international team of scientists lead by Jean-Baptiste Vincent at the Max Planck Institute found that those sinkholes may turn into jet sites that sling off ice and gases. What’s more, the pits help reveal what’s underneath the comet’s surface: dinosaur eggs.

Okay, that might be a little misleading. As Vincent tells Wired, “In the walls of these pits there are strange things, though we don’t fully understand what they are. … We see lots of fractures and features that look like pebbles—some people call them ‘dinosaur eggs.’ They look like the primordial pieces that make up the comets to begin with.”

Scientists are still trying to discern how exactly the comet takes this shape. The study authors think the process is probably the same as how sinkholes here on Earth form: by a porous interior eating away at material to create a hollow cavity under the surface. If they can figure out the precise mechanism, it will help them explain how comets form and how they behave.

Rosetta still has a lot more data to collect before the end of its mission in September 2016 (in which it will possibly attempt to land on the comet’s surface). As 67P approaches the sun, the sinkhole jets will start to spew up bigger and badder materials. Rosetta will try to use its chemical sensing instruments to better analyze more of the comet’s physical makeup. It’s going to be a fun ride.